Gas turbine engine rotors, such as fan, compressor and turbine rotors, can be balanced by removal of material. The material removal process usually involves milling a groove into a surface of the rotor to correct the unbalance. These grooves may create high stress areas in the rotor. In addition, the portion of the rotor in which the groove is formed must typically be over dimensioned to ensure sufficient depth of material can be removed in forming the groove, which may add significant weight to the rotor.
The rotors can also be balanced through the addition of rings having a fixed geometry including eccentricities which are detachably engaged to the rotor by varying the relative angle between the rings depending on the unbalance to be corrected, or through the addition of balancing weights attached to the rotor. Both methods may also add significant weight to the rotor.